Accessory to allow sensing at balloon interface

ABSTRACT

A device, system and method for temperature-based lesion formation assessment and mapping functionality using an accessory usable with an over-the-wire balloon catheter. The device may include a first annular element, a plurality of wires coupled to the first annular element, and a second annular element, the plurality of wires passing from the first annular element through the second annular element and into an elongate wire conduit coupled to the second annular element. At least one of the plurality of wires may include at least one temperature sensor and/or at least one mapping electrode. The first annular element coupled to an outer surface of a sheath. As a balloon catheter is advanced out of the sheath lumen, the distal tip of the catheter engages the second annular element and pushes the wires out of the sheath lumen, everting them over the balloon of the catheter.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of and claims priority to patentapplication Ser. No. 14/169,269, filed Jan. 31, 2014, entitled ACCESSORYTO ALLOW SENSING AT BALLOON INTERFACE, the entirety of which isincorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

n/a

FIELD OF THE INVENTION

The present invention relates to a method and system for a cryoablationsystem and device that allows for accurate temperature-based lesionformation assessment and mapping functionality using a relativelyinexpensive catheter accessory that may be used on any aftermarket,over-the-wire balloon catheter.

BACKGROUND OF THE INVENTION

A cardiac arrhythmia is a condition in which the heart's normal rhythmis disrupted. There are many types of cardiac arrhythmias, includingsupraventricular arrhythmias that begin above the ventricles (such aspremature atrial contractions, atrial flutter, accessory pathwaytachycardias, atrial fibrillation, and AV nodal reentrant tachycardia),ventricular arrhythmias that begin in the lower chambers of the heart(such as premature ventricular contractions, ventricular tachycardia,ventricular fibrillation, and long QT syndrome), and bradyarrhythmiasthat involve slow heart rhythms and may arise from disease in theheart's conduction system.

Catheter ablation is commonly used to treat a variety of cardiovascularconditions, such as cardiac arrhythmias, atrial fibrillation, and otherirregularities in the transmission of electrical impulses through theheart. This minimally invasive surgical technique may involve the use oftip electrodes, electrode arrays, cryoballoons, and/or other ablatingelements to create lesions or other anatomical effects that disrupt orblock electrical pathways through the targeted tissue.

The success of this procedure depends largely on the quality of thelesion(s) created during the procedure. In theory, the most accurate wayto assess lesion formation is by monitoring the temperature of thetissue being ablated. However, measuring the temperature of treatedtissue during a procedure may be difficult or impossible using knowndevices and methods, and integrating temperature sensors into theablation device can increase the size, complexity, and cost of thedevice. Further, methods that measure temperature within the cryoballoonto approximate the temperature of treated tissue may not take intoaccount the tissue type and response to treatment, and can be veryinaccurate. Likewise, temperature-time assessment methods may be basedon a one-size-fits-all model that does not take into account the typeand depth of tissue, and may be subject to noise in the temperaturedata.

Further, in the treatment of cardiac arrhythmias, a specific area ofcardiac tissue having aberrant electrical activity (e.g. focal trigger,slow conduction, excessively rapid repolarization, fractionatedelectrogram, etc.) is typically identified first before subsequenttreatment. This process, sometimes referred to as localization ormapping, can include obtaining unipolar or bipolar electrograms, ormonophasic action potential (“MAP”) electrograms of a particular cardiacregion. MAP signals may be obtained by temporarily depolarizing selectedtissue, which responsive electrical activity being recorded or otherwisemonitored for an indication of local depolarization timing, refractoryperiod duration, and any aberrant electrical activity. After mapping anddiagnosing aberrant tissue, a physician may decide to treat the patientby ablating the tissue. Accurate mapping of the cardiac tissue usingbipolar, unipolar, or MAP electrogram signals can reduce the number ofablations necessary to treat an aberrant electrical pathway, and canmake the executed ablations more effective. Additionally, MAP recordingscan substantially improve the ability to determine the timing of localtissue activation, which is often ambiguous when recorded using standardintracardiac electrodes.

Presently, this procedure may require mapping an area of tissue with afirst mapping device. Once an optimal ablation site is identified, themapping device is withdrawn and replaced with an ablation device.However, this practice may increase the chances of patient injury orprocedure complications, and may disadvantageously increase the totaltime needed to treat a condition. Alternatively, presently known devicesmay include mapping and ablation functionality in a single device, whichmay reduce procedure time and complexity by eliminating the need toemploy separate mapping and ablation devices for each task. Combinationmapping and ablation devices also increase ablation accuracy, becauseonce aberrant tissue (the “target tissue”) is found, ablation can beginimmediately without having to remove the mapping device and relocatingthe target tissue with the ablation device. However, such devices mayrequire complicated manufacturing steps and expensive materials, maypresent insulation problems between mapping and ablation electrodes, andthe devices themselves may be prohibitively expensive for some surgeons.

Therefore, it is desirable to provide a cryoablation system, device, andmethod that allows for accurate temperature-based lesion formationassessment and mapping functionality using a relatively inexpensivecatheter accessory that may be used on any aftermarket, over-the-wireballoon catheter.

SUMMARY OF THE INVENTION

The present invention advantageously provides a method and system forevaluating tissue, such as by providing an accessory that allows fortemperature-based lesion formation assessment and mapping functionality.The accessory may be used on an aftermarket, over-the-wire ballooncatheter. In one embodiment, the accessory may include a first annularelement, a plurality of wires coupled to the first annular element, anda second annular element, the plurality of wires passing from the firstannular element through the second annular element. The accessory mayfurther include an elongate wire conduit coupled to the second annularelement, with the plurality of wires passing through the second annularelement and into the wire conduit. At least one of the plurality ofwires may include at least one temperature sensor and/or at least onemapping electrode, and may further include at least one referenceelectrode. For example, the accessory may include four wires with eachwire including a temperature sensor and a mapping electrode and,optionally, one of the wires may include a reference electrode. Theaccessory may further include a sheath having a distal portion, aproximal portion, and a lumen therebetween, and the sheath lumen may besized to receive a balloon catheter within when the balloon is deflated.The first annular element may be coupled to an outer surface of thedistal portion of the sheath, and the second annular element and atleast a portion of each wire may be disposed within the sheath lumen.The medical device may be an over-the-wire device, such as a ballooncatheter, having a lumen that is sized to receive the elongate wireconduit. A proximal face of the second annular element may be configuredto be engageable with a distal tip of a medical device. For example, theproximal face of the second annular element may be configured to bematably engageable with a distal tip of the medical device.

A medical system for evaluating tissue may generally include an elongatesheath having a proximal portion, a distal portion, and a lumentherebetween, a first annular element coupled to an outer surface of thedistal portion of the sheath, a plurality of wires coupled to the firstannular element, at least one of the plurality of wires including atleast one sensor element, an elongate wire conduit disposed within thesheath lumen, the wire conduit having a proximal portion, a distalportion, and a lumen therebetween, and a second annular element coupledto the distal portion of the wire conduit, at least a portion of each ofthe plurality of wires passing through the second annular element andbeing disposed within the lumen of the wire conduit. The at least onesensor element may include a temperature sensor and/or a mappingelectrode. Further, at least one of the plurality of wires may include areference electrode. For example, each wire may include one or moretemperature sensors and one or more mapping electrodes. The firstannular element may include a distal edge, a proximal edge, an innersurface, and an outer surface, and each of the plurality of wires mayinclude a proximal portion and a distal portion. A first portion of thedistal portion of each of the plurality of wires may be coupled to theouter surface of the first annular element, a second portion of thedistal portion of each of the plurality or wires may pass over thedistal edge of the annular element, and a third portion of the distalportion of each of the plurality of wires may pass within the annularelement proximate the inner surface of the annular element. The secondannular element may include a proximal face and a distal face, theproximal face being configured to be releasably engageable with a distaltip of a medical device. The system may further include a control unitincluding a processor, the processor being configured to receive signalsfrom the at least one sensor element. For example, the processor maycause the control unit to generate an alert based at least in part onsignals received from the at least one sensor element.

A method for evaluating tissue may generally include advancing a ballooncatheter having an uninflated balloon through a lumen of a sheath, thesheath including a first annular element coupled to a distal portion ofthe sheath, a plurality of wires coupled to an outer surface of thefirst annular element, and a second annular element coupled to anelongate wire conduit, at least a portion of each of the plurality ofwires being disposed through the second annular element and within thewire conduit, the wire conduit, second annular element, and at least aportion of each of the plurality of wires being disposed within thesheath lumen; releasably engaging a distal tip of the balloon catheterwith the second annular element; advancing the balloon catheter throughthe sheath lumen until the uninflated balloon, the second annularelement, and at least a portion of each of the plurality of wires arelocated distal to the distal portion of the sheath; and inflating theballoon, at least a portion of each of the plurality of wires beingdisposed over the inflated balloon. At least one of the plurality ofwires may include at least one sensing element, and the method mayfurther include recording a physiological measurement with the at leastone sensing element. The at least one sensing element may be atemperature sensor or a mapping electrode. For example, each wire mayinclude both a temperature sensor and a mapping electrode. One of theplurality of wires may also include a reference electrode. The methodmay further include retracting the balloon catheter, the second annularelement, and at least a portion of each of the plurality of wires withinthe sheath lumen; and further retracting the balloon catheter within thesheath lumen until the distal tip of the balloon catheter disengagesfrom the second annular element.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention, and theattendant advantages and features thereof, will be more readilyunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings wherein:

FIG. 1 shows an exemplary medical system including an over-the-wireballoon catheter;

FIG. 2A shows a side perspective view of a balloon catheter accessoryincluding temperature sensing and/or mapping functionality;

FIG. 2B shows an anterior view of a balloon catheter accessory includingtemperature sensing and/or mapping functionality;

FIGS. 3-7 show a series of steps for deploying a balloon catheter in usewith a balloon catheter accessory;

FIGS. 8A and 8B show a close-up view of an exemplary embodiment of astopper of a balloon catheter accessory;

FIGS. 9A and 9B show a close-up view of a further exemplary embodimentof a stopper of a balloon catheter accessory; and

FIGS. 10-14 show a series of steps for deploying a balloon catheter inuse with a balloon catheter accessory in a patient's heart.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a cryoablation system, device, and methodthat allows for accurate temperature-based lesion formation assessmentand mapping functionality using a relatively inexpensive catheteraccessory that may be used on any aftermarket, over-the-wire ballooncatheter. Referring now to the figures, which are not necessarily drawnto scale and are not intended to limit the scope of the invention, inwhich similar elements in different drawings are numbered with likereference numbers, an exemplary medical system 10 is shown in FIG. 1.The system 10 may generally include an over-the-wire medical device 12that may be coupled to a control unit 14 or operating console and amodified sheath, including a standard sheath 16 to which an accessory 18having temperature sensing and/or mapping functionality is coupled orattached. The medical device 12, for example, a cryoablation device asshown in FIG. 1, may generally include an elongate body 20 and one ormore treatment elements 22 for energetic, therapeutic and/orinvestigatory interaction between the medical device 12 and a treatmentsite. For example, the treatment element 22 may include an expandableelement, such as a balloon 24. The treatment element 22 may deliver, forexample, cryogenic therapy to a tissue area in proximity to a treatmentregion, including cardiac tissue and/or pulmonary vein tissue.

Continuing to refer to FIG. 1, the elongate body 20 may be passablethrough a patient's vasculature and/or proximate to a tissue region fordiagnosis or treatment. Accordingly, the elongate body 20 may becomposed of a biocompatible material that is sufficiently flexible tosafely pass through tortuous pathways of the patient's vasculature. Theelongate body 20 may define a proximal portion 26 and a distal portion28, and may further include one or more lumens or conduits disposedwithin the elongate body 20 thereby providing mechanical, electrical,and/or fluid communication between the proximal portion of the elongatebody 20 and the distal portion of the elongate body 20, such as a mainlumen 30 as discussed in more detail below. The proximal portion 26 ofthe elongate body 20 may include a handle 32 having one or more knobs,levers, connectors, umbilicals, and other components used for steering,manipulating, and operating the device 12 and connecting the device 12to the control unit 14.

The medical device 12 may further include an elongate guidewire lumen 34at least partially disposed within a portion of the elongate body 20,such as the main lumen 30. The guidewire lumen 34 may extend orotherwise protrude from a distal end of the elongate body 20, and may bemovable with respect to the elongate body 20 in longitudinal androtational directions. That is, the guidewire lumen 34 may be slidablyand/or rotatably moveable with respect to the elongate body 20.Alternatively, the guidewire lumen 34 may be affixed or coupled to theelongate body 20 such that the guidewire lumen 34 has a fixed positionand is not slidably and/or rotatably moveable with respect to theelongate body 20.

The treatment element 22 may be located at a distal end of the device12, and may, for example, be coupled to the distal portion 28 of theelongate body 20. As shown in FIG. 1, for example, the treatment element22 may be a balloon 24, although it will be understood that thetreatment element 22 may include more than one expandable element orballoon. The balloon 24 may include a proximal portion 36 and a distalportion 38, and may define an interior chamber or region 40 that is influid communication with a fluid delivery conduit 42 for providing fluidor coolant to the interior chamber 40 and a fluid recovery conduit 44for the removal of expended coolant or other fluid from the interior 40of the balloon 24. In the non-limiting embodiment shown in FIG. 1, theproximal portion 36 of the balloon 24 may be coupled to the distalportion 28 of the elongate body 20 and the distal portion 38 of theballoon 24 may be coupled to the distal portion 46 of the guidewirelumen 34, proximate a distal tip 48 of the device 12.

The proximal 36 and distal portion 38 of the balloon 24 may be coupledto the guidewire lumen 34 or elongate body 20 using, for example, abiocompatible adhesive. The balloon 24 may further include one or morelayers providing for puncture resistance, radiopacity, or the like (forexample, a second balloon disposed about the balloon 24), and may alsobe substantially electrically insulative. The balloon 24 may be composedof a compliant (for example, polyurethane [PU] of nylon elastomers) ornon-compliant or semi-compliant material (for example, polyethyleneterephthalate [PET] or nylon).

The device 12 may further include a fluid delivery lumen or conduit 42that is in fluid communication with a fluid supply 52 to deliver a fluid(for example, coolant, saline, or other fluid) from the proximal portion26 of the elongate body 20 and/or the control unit 14 to the distalportion 28 of the elongate body 20 and/or treatment element 22 of thedevice 12. Additionally, the device 12 may further include a fluidrecovery lumen or conduit 44 that is in fluid communication with thescavenging system. The fluid delivery conduit 42 and fluid recoveryconduit 44 may be included in or defined by either the elongate body 20and/or guidewire lumen 34. If the fluid delivery conduit 42 is includedin or defined by the guidewire lumen 34, the guidewire lumen 34 mayinclude one or more fluid ejection ports for expelling fluid into theinterior chamber 40 of the balloon 24 (not shown). Alternatively, thefluid delivery conduit is disposed within the elongate body 20, thefluid delivery conduit may extend into the balloon 24 in a parallel orsubstantially parallel fashion to the guidewire lumen 34, or may insteadbe coiled about or otherwise encircling or disposed about the guidewirelumen 34 (as shown in FIG. 1).

The system 10 may include one or more treatment or diagnostic sourcescoupled to the device 12 for use in an operative procedure, such astissue ablation. For example, the control unit 14 may include a fluidsupply 52 including one or more reservoirs for one or more coolants,cryogenic refrigerants, saline, or the like, an exhaust or scavengingsystem for recovering or venting expended fluid for reuse or disposal,as well as various control mechanisms. In addition to providing anexhaust function for the fluid supply 52, the control unit 14 may alsoinclude a fluid recovery reservoir 54, one or more pumps 56, valves,controllers or the like to recover and/or re-circulate fluid deliveredto various fluid pathways of the medical device 12. A vacuum pump 56 inthe control unit 14 may create a low-pressure environment in one or moreconduits within the medical device 12 so that fluid is drawn into theconduits/lumens of the elongate body 20, away from the distal portionand toward the proximal portion of the elongate body 20.

The control unit 14 may also include one or more components for themanual and/or automatic regulation of the system, such as a computer 58having a processor 60 for executing one or more algorithms for theautomatic regulation of the device 12 before, during, and after anablation procedure. For example, the processor 60 may be programmable toinflate and deflate one or more cryoballoons of the treatment element(such as according to a user-programmed duty cycle or an automated dutycycle), to regulate temperature of the treatment element, and/or toreceive and interpret physiological measurement signals, for example,temperature and/or mapping signals, from the cryoablation device 12 oranother device used as part of a medical procedure. Although varioussystem components may be shown and described herein as being within thecontrol unit 14, the term “control unit” as used herein refers to anysystem component other than the cryoablation device 12 and other devicesthat are passed into the patient to perform the medical procedure,regardless of whether the components are physically located within thecontrol unit 14.

The medical system 10 may further include a catheter sheath 16 that maybe inserted into the patient's vasculature prior to insertion of theablation device 12, using methods known in the art. For example, asshown and described in more detail in FIGS. 3-7 and 10-14, the sheath 16may be passed through the vasculature into an area proximate the targettissue (referred to as the target treatment site), such as the leftatrium of the heart. Once the sheath 16 is positioned in the desiredlocation, the ablation device 12 may be passed within the sheath 16,using methods known in the art, to the target treatment site. In manyknown systems and methods, the sheath 16 is removed or partially removedfrom the patient's body before an ablation procedure, leaving only theablation device 12 proximate the target treatment site. In the presentsystem, however, the sheath 16 is allowed to remain at a locationproximate the treatment element 22 and the target treatment site, forreasons shown and described in more detail in FIGS. 1-14. The sheath 16may or may not be in communication with the control unit 14.

Referring now to FIGS. 1-2B, an accessory having temperature sensingand/or mapping functionality that may be used in association with anover-the-wire medical device 12 is shown. The accessory 18 may generallyinclude an elongate and flexible wire conduit 62, an annular stopper 64,a plurality of wires 66, and an annular anchor element 68. Although fourwires 66 radially spaced approximately 90° apart are shown in FIGS. 2Aand 2B, it will be understood that any number of wires 66 may be used.As shown in FIG. 2A, the wire conduit 62 may be coupled to or integratedwith the stopper 64, with the stopper 64 having a larger outer diameterOD_(S) than the outer diameter OD_(WC) of the wire conduit 62. Forexample, the stopper 64 and wire conduit 62 may be manufactured from asingle piece of material, such as Nitinol, stainless steel, polymer, orcombinations thereof, or may be adhered or bonded to the wire conduit 62using a biocompatible adhesive, bonding agent or welding or soldering,or the stopper 64 may be overmolded on the wire conduit 62. The materialfrom which at least the wire conduit 62 is composed may be flexibleenough to allow the wire conduit 62 to function as a guide wire lumenthrough the balloon. Further, the outer diameter OD_(WC) of the wireconduit 62, and not the outer diameter OD_(S) of the stopper 64, may besized to pass within a lumen (for example, the main lumen 30) and/or theguidewire lumen 34 of the device 12. The outer diameter OD_(ST) of thestopper 64 may be sized to pass within the inner diameter ID_(SH) of thesheath 16.

The wire conduit 62 may be hollow and the stopper 64 may be annular witha center opening 70 having approximately the same inner diameter as theinner diameter of the wire conduit 62, such that at least a portion ofeach wire 66 passes through the opening 70 and into the wire conduit 62.For example, a portion of each wire 66 may be disposed within the wireconduit 62 from the stopper to a proximal end 72 of the wire conduit 62.The portions of the stopper 64 surrounding the center opening 70 may becomposed of a low-friction material, may have rounded edges, and/or mayinclude other features that promote free movement of the wires 66 overthe stopper 64 without causing damage to or kinking or bending the wires66. Further, a distal portion 74 of each wire 66 may extend out of andbeyond a distal portion 76 of the wire conduit 62, and a proximalportions 78 of the wires 66 may be bundled within the proximal portion72 of the wire conduit (as shown in FIGS. 1 and 2). The proximalportions 78 of the wires 66 may be in electrical communication with thecontrol unit 14, and the processor 60 may be configured and programmableto receive and interpret temperature and/or mapping signal data from theaccessory 18.

The anchor element 68 may be removably or permanently coupled to oraffixed to a distal portion 80 of the sheath (for example, as shown inFIGS. 3-7). For example, the anchor element 68 may be composed of amagnetic metal and a distal portion 80 of the sheath 16 may bemagnetized, such that an inner surface 82 of the anchor element 68 ismagnetically coupled to the distal portion 80 of the sheath 16. Thestrength of this coupling may depend on the strength of the magneticattraction between the anchor element 68 and the sheath 16. In any case,however, the anchor element 68 may stay coupled to the sheath 16 whilethe sheath 16 remains inside the patient's body. Alternatively, theinner surface 82 of the anchor element 68 may be adhered to an outersurface 84 of the sheath 16, such as by the use of a biocompatibleadhesive or bonding agent. Alternatively, the distal portion 80 of thesheath 16 may have a metal component to which an inner surface 82 of theanchor element 68 may be welded or anchored. As a non-limiting example,the inner diameter ID_(AE) of the anchor element 68 may be betweenapproximately 12 French and approximately 15 French.

At least a portion of the distal portion 74 of each wire 66 may becoupled to or affixed to an outer surface 86 of the anchor element 68.For example, a portion of each wire 66 may be anchored to or welded tothe outer surface 86 of the anchor element 68 at one or more attachmentpoints 88, depicted in FIG. 2A with hatch marks. From the attachmentpoints 88, each wire 66 may pass over the distal edge 90 of the anchorelement 68, pass within the anchor element 68 past the proximal edge 92,through the center opening 70 of the stopper 64, and into the wireconduit 62. Thus, the wires 66 may be disposed within the wire conduit62, which, in turn, is within the sheath 16. In this manner, the wires66 may be easily advanced out of the wire conduit 62 when the medicaldevice 12 pushes on the stopper 64 and exits the sheath 16.

Each wire 66 may include at least one temperature sensor 96 and/or atleast one mapping electrode 98. In the non-limiting embodiment shown inFIGS. 3-7, each wire may include one temperature sensor 96 and onemapping electrode 98. Additionally, at least one wire 66 may include areference electrode 106, if monophasic action potential (MAP)electrograms are to be recorded. Otherwise, no reference electrode maybe included. The temperature sensors 96 may be thermocouples or othersensors known in the art. Additionally or alternatively, the one or moresensors may be other types of sensors, such as pH sensors, pressuresensors, or the like. Each sensor 96 may be of any size andconfiguration that is suitable for lying against or in contact with aninflated balloon without rupturing or damaging the balloon, even whenthe balloon pushes the sensor 96 against myocardial tissue. Stillfurther, each sensor 96 may be sized and shaped to ensure optimalcontact with tissue during use.

The mapping electrodes 98 may be composed of a conductive metal andconfigured to record, for example, monopolar, bipolar, or monophasicaction potential (MAP) electrograms. MAP electrograms, for example, maydocument the onset of local tissue depolarization, repolarization, andthe general action potential morphology. The MAP signal may be generatedby measurement between a mapping electrode 98 and a reference electrode106. The reference electrode 106 may be in contact with the blood butgenerally not in contact with the myocardium, and the mapping electrode98 may be in contact with the myocardium, with high enough localpressure to depolarize the underlying myocytes. To produce thisincreased local pressure, each mapping electrode 98 may be configured toprotrude from the surface of the balloon 24 when the accessory 18 isengaged with the balloon 24. For example, the mapping electrodes may bedome shaped or have a rounded surface, may have one or moreprotuberances, or may have other geometries or textures that enhancecontact with the myocardial tissue. Inflation of the balloon 24 againstthe mapping electrodes 98 may facilitate creating the necessary pressurebetween the mapping electrodes 98 and the target tissue. Further,although the mapping electrodes 98 may be positioned at any point alongthe distal portion 74 of each wire 66, the mapping electrodes 98 andtemperature sensors 96 may be located at a position along the wire 66that will be in contact with, or proximate, the area of the balloon 24corresponding to the location where the pressure on the mappingelectrodes 98 and temperature sensors 96 against the target tissue maybe the greatest. As a non-limiting example, this location on a 28 mmballoon may be the area at which the balloon has a diameter of betweenapproximately 15 mm and approximately 25 mm. When the balloon is pushedagainst the pulmonary vein ostium, the balloon may become at leastpartially compressed, giving the anterior portion of the balloon asomewhat conical shape. Although the distal tip of the device 12 may beadvanced to a distance within the pulmonary vein, most of the balloon,including the portion anterior of the widest balloon outer diameterOD_(BW), may remain in contact with the pulmonary vein ostium. Thus,optimal placement of the electrodes 98 and sensors 96 may be anterior tothe widest outer diameter OD_(BW), but proximal of the distal tip 48 ofthe device 12.

The proximal portion 72 of the wire conduit 62 and or the proximalportions 78 of the wires 66 may collectively be in electricalcommunication with an electrical connector 99 that is connectable to thecontrol unit 14. However, the proximal portion 72 of the wire conduit 62may be removably coupled to the connector 99 to allow the medical device12 to be advanced over the wire conduit 62. The control unit 14, forexample, the processor 60, may be configured and programmable to receiveand interpret temperature and/or mapping signal data from the one ormore temperature sensors 96 and/or mapping electrodes 98 through thewires 66. The processor 60 may be programmable to execute an algorithmthat uses the received data to suggest to the user and/or automaticallycause the control unit 14 to carry out a particular command, such asincreasing the flow of coolant into the balloon 24, increasing thetemperature of the balloon 24, inflate or deflate the balloon 24,display to the user an image of the patient's heart on which suggestedor recommended ablation locations are shown, disable the temperaturesensors 96, or other function that may enhance the effectiveness of theablation or treatment procedure. Further, the processor 60 may beconfigured and programmable to cause the control unit 14 to broadcast anaudible or visual alert to the user, which may notify the user that,based at least in part on signals received from the one or moretemperature sensors 96 and/or mapping electrodes 98, the device 12 is atan optimal ablation site, is not at an optimal ablation site, thatablation depth is sufficient to create a permanent lesion, that ablationdepth may have reached non-target tissue, or any of a variety ofindications relating to the ablation or treatment procedure.

Referring now to FIGS. 3-7, a series of steps for deploying a ballooncatheter in use with a balloon catheter accessory are shown. In anexemplary method of deployment, the anchor element 68 of the accessory18 may be coupled to the distal portion 80 of the sheath 16, with thewires 66, stopper 64, and wire conduit 62 being disposed within thesheath 16. As shown in FIG. 3, an over-the-wire balloon catheter 12 maybe advanced over the wire conduit 62 with the balloon 24 in anuninflated configuration. At this stage, the stopper 64 may be at alocation proximal to the anchor element 68. The balloon catheter 12 maybe advanced over the wire conduit 62 until the distal tip 48 of thedevice 12 comes into contact with the stopper 64. As is shown anddescribed in more detail in FIGS. 8A-9B, at least a portion of thestopper 64 may have a configuration that is matable with the devicedistal tip 48. Alternatively, the device distal tip 48 may have anannular distal face 100 that encircles the distal opening of theguidewire lumen 34, and the stopper 64 may include an annular proximalface 102 that encircles the outer diameter of the wire conduit 62, bothof which faces 100, 102 being substantially orthogonal to thelongitudinal axis 104 of the device 12. As shown in FIGS. 3-7, thedistal face 100 of the device distal tip 48 may abut the proximal face102 of the stopper 64. No matter the configuration of the interfacebetween the device distal tip 48 and the stopper 64, further advancementof the device 12 over the wire conduit 62 may advance the stopper 64through the sheath 16 and out the distal portion 80 of the sheath 16 (asshown in FIG. 4).

As shown in FIGS. 4 and 5, advancement of the stopper 64 within thesheath 16 may cause the wires 66 to protrude distally from the anchorelement 68 as they are pushed away from the distal edge 90. However, atleast a portion of the distal portion 74 of each wire 66 may remainaffixed to the outer surface 86 of the anchor element 68 at theattachment points 88. Likewise, the anchor element 68 may remain coupledto the distal portion 80 of the sheath 16.

As shown in FIG. 6, once the balloon 24 has been advanced past thedistal portion 80 of the sheath 16, the balloon 24 may be inflated, suchas by the initiation of flow of a fluid (for example, a coolant) throughthe fluid delivery conduit 42 from the fluid supply 52 into the interiorchamber 40 of the balloon 24. The distal portion 74 of each wire 66 thatis exposed from the wire conduit 62 (that is, that extends distally fromthe stopper 64) may be long enough such that the wires 66 lie againstthe expanded balloon 24 just loosely enough to avoid damaging ordistorting the balloon 24 but snugly enough that the wires 66 don't kinkor bend, and that sufficient pressure is exerted against the one or moretemperature sensors 96 and mapping electrodes 98 against the targettissue when the balloon 24 is in contact with the target tissue. Asshown in FIGS. 5 and 6, deployment of the device 12 beyond the sheath 16essentially everts the wires 66 of the accessory 18, and causes thestopper 64 to extend beyond (distal to) the anchor element 68. If areference electrode 106 is used, it may be disposed on a wire 66proximate the anchor element 68, such that the reference electrode 106is positioned proximal to the expanded balloon 20, thus reducing thelikelihood that the reference electrode 106 would be in contact with thetarget tissue.

As shown in FIG. 7, the device 12 may be retracted or withdrawn throughthe sheath 16 toward the proximal portion 107 of the sheath 16. At acertain point within the sheath 16, the device distal tip 48 may becomedisengaged from the stopper 64 and the device 12 may be removed from thepatient's body, leaving the accessory 18 attached to the sheath 42. Forexample, the inner lumen of the sheath 16 may include a protrusion orridge 108 that prevents the stopper 64 from retracting further withinthe sheath 16 but allows passage of the device distal tip 48, therebycausing the device distal tip 48 to disengage. This protrusion or ridge108 may be a tab-like protrusion from an inner surface of the innerlumen or may be an annular ridge that encircles or partially encirclesat least a portion of the inner lumen. Alternatively, the device distaltip 48 may become disengaged from the stopper 64 when the stopper 64 isretracted far enough within the sheath 16 to cause the distal portions74 of the wires 66 to go taught, the force of which will prevent thestopper 64 from being retracted farther. While the sheath 16 is beingremoved from the patient's body, the stopper 64 may be retained withinthe sheath 16 by a gentle pull force exerted on the proximal portions 78of the wires 66 and/or the proximal portion 72 of the wire conduit 62.

Referring now to FIGS. 8A-9B, close-up views of exemplary embodiments ofa stopper of a balloon catheter accessory are shown. As discussed aboveregarding FIGS. 3-7, the at least a portion of the stopper 64 may have aconfiguration that is matable with the device distal tip 48 and is usedto removably engage the device distal tip 48 with the stopper 64. Tofacilitate engagement between the stopper 64 and device distal tip 48,the user may apply a counterforce (that is, pulling force) in thestopper 64 against the pushing force of the device distal tip 48 bygently pulling on the proximal portions 78 of the wires 66 and/or theproximal portion 72 of the wire conduit 62, which may be located outsidethe patient's body. Additionally or alternatively, the wire conduit 62and the stopper 64 may each include a magnet, such that the twocomponents may be magnetically attracted to each other.

In the non-limiting embodiment shown in FIGS. 3-7, the device distal tip48 may have a planar or substantially planar annular distal face 100 andthe stopper 64 may include a planar or substantially planar annularproximal face 102, both of which being substantially orthogonal to thelongitudinal axis 104 of the device 12. In contrast, the non-limitingembodiments shown in FIGS. 8A-9B may include non-planar geometry. Forexample, as shown in FIGS. 8A and 8B, the annular distal face 100 of thedevice distal tip 48 may include one or more protuberances 110, whichmay be, for example, dome-shaped or peg-shaped. Similarly, the annularproximal face 102 of the stopper 64 may include one or more indentations112 corresponding to the protuberances 110 of the distal face 100 of thedevice distal tip 48. Thus, the one or more protuberances 110 may bematably engageable with the one or more indentations 112, providing aremovable coupling between the device 12 and the accessory 18. Todisengage the device 12 from the stopper 64 of the accessory 18, thedevice 12 may be retracted away from the stopper 64, which will causethe protuberances 110 to separate from the corresponding indentations112.

In the non-limiting embodiment shown in FIGS. 9A and 9B, the annulardistal face 100 of the device distal tip 48 may include one or moreposts 114, each of which including a rounded or angular lip 116 at thedistal end. Similarly, the annular proximal face 102 of the stopper 64may include one or more L-shaped or curved tracks 118 configured toreceive and lock the lip 116 of each post 114 within the track 118. Forexample, the device 12 may be advanced over the wire conduit 62 towardthe stopper 64 until each post 114 of the device distal tip 48 matablyengages with a portion 120 of the corresponding track 118 that issubstantially parallel to the longitudinal axis 104 of the device 12.Then, the device 12 may be rotated in the direction to which thesubstantially transverse portion 122 of the corresponding track 118 isextended. This rotation may lock the device 12 to the stopper 64 of theaccessory 18. To disengage the device 12 from the accessory 18, thedevice 12 may be rotated in the opposite direction and the posts 114 maybe retracted from the longitudinal portion 120 of the track 118.

Referring now to FIGS. 10-14, a series of steps for deploying a ballooncatheter in use with a balloon catheter accessory in a stylizedrendering of a patient's heart is shown. The steps shown in FIGS. 10-14are generally the same as those of FIGS. 3-7, but are shown within theheart at a non-limiting example of a target treatment site, the leftatrium. As shown in FIG. 10, the sheath 16 with attached accessory 18may be passed through the patient's vasculature and positioned at alocation proximate a target treatment site. For example, the sheath 16and accessory 18 are shown in the left atrium. Although FIG. 10 showsthe left atrium having been accessed through puncture of the septumbetween the right atrium and the left atrium, it will be understood thatother methods of accessing the left atrium may be used, and targettreatment sites other than the left atrium may be desired.

As shown in FIG. 11 (showing a close-up view of the left atrium), thedevice 12 may be advanced within the sheath 16 over the wire conduit 62until the device distal tip 48 comes into contact with the stopper 64and, depending on the configurations of the distal face 100 of thedevice distal tip 48 and proximal face 102 of the stopper 64, the device12 matably engages with the accessory 18. The device 12 then continuesto be advanced within the sheath 16 until the balloon 20 is outside thesheath 16 (as shown in FIG. 12). In this step, the plurality of wires 66may become everted and may extend proximally over the outer surface ofthe balloon 20 from the stopper 64 to the anchor element 68. As shown inFIG. 13, the balloon 20 may be inflated, for example, by initiating orincreasing the flow of coolant or other fluid from the fluid supply 52into the interior chamber 40 of the balloon 20. The inflated andexpanded balloon 20 may provide pressure against the inner surfaces ofthe one or more temperature sensors 96 and/or the one or more mappingelectrodes 98 to enhance contact between the outer surfaces of the oneor more temperature sensors 96 and/or the one or more mapping electrodes98 and the target myocardial tissue. Once the balloon 20 is inflated,the control unit 14 may receive temperature measurement signals from theone or more temperature sensors 96 and/or mapping signals from the oneor more mapping electrodes 98. Thus, the accessory 18 may providetemperature sensing and/or mapping functionality to a standard ballooncatheter 12 without the complication of attaching or integrating thesensors 96 and/or mapping electrodes 98 to the device 12 itself.

As shown in FIG. 14, the device 12 may be retracted or withdrawn throughthe sheath 16 toward the proximal portion 107 of the sheath 16 forremoval of the device 12 from the patient's body. At a certain pointwithin the sheath 16, the device distal tip 48 may become disengagedfrom the stopper 64, as shown and described in FIG. 7. The device 12 mayfirst be completely removed from the patient's body and from within thesheath 16, followed by removal of the sheath 16 with attached accessory18 from the patient's body. Alternatively, the device 12 may beretracted to a certain distance within the sheath 16, and the sheath 16with attached accessory 18 and the device 12 may together be removedfrom the patient's body.

It will be appreciated by persons skilled in the art that the presentinvention is not limited to what has been particularly shown anddescribed herein above. In addition, unless mention was made above tothe contrary, it should be noted that all of the accompanying drawingsare not to scale. A variety of modifications and variations are possiblein light of the above teachings without departing from the scope andspirit of the invention, which is limited only by the following claims.

What is claimed is:
 1. A method of evaluating tissue, the methodcomprising: inserting a medical device within a lumen of a sheath, themedical device being slidably movable within the sheath, the medicaldevice having: an inflatable element at a distal portion of the medicaldevice, the inflatable element being uninflated; a distal tip at thedistal portion of the medical device; a first annular element coupled toan outer surface of a distal portion of the sheath; a plurality of wirescoupled to the first annular element, at least one of the plurality ofwires including at least one sensor element; an elongate wire conduitdisposed within the sheath lumen, the wire conduit having a proximalportion, a distal portion, and a lumen therebetween; and a secondannular element coupled to the distal portion of the wire conduit, atleast a portion of each of the plurality of wires passing through thesecond annular element and being disposed within the lumen of the wireconduit; advancing the medical device through the lumen of the sheathuntil the inflatable element and the distal tip are positioned beyond adistal portion of the sheath and the distal dip is engaged with thesecond annular element and the plurality of wires are disposed over anouter surface of the inflatable element; inflating the inflatableelement; and recording a physiological measurement with the at least onesensing element.
 2. The method of claim 1, further comprising:retracting the medical device, the second annular element, and at leasta portion of each of the plurality of wires within the lumen of thesheath; and further retracting the medical device within the lumen ofthe sheath until the distal tip of the medical device disengages fromthe second annular element.
 3. The method of claim 1, wherein the atleast one sensor element includes at least one of a temperature sensorand a mapping electrode.
 4. The method of claim 3, wherein at least oneof the plurality of wires includes a mapping electrode and at least oneof the plurality of wires further includes a reference electrode.
 5. Themethod of claim 3, wherein each of the plurality of wires includes atleast one temperature sensor and at least one mapping electrode.
 6. Themethod of claim 1, wherein the first annular element includes a distaledge, a proximal edge, an inner surface, and an outer surface, and eachof the plurality of wires include a proximal portion and a distalportion.
 7. The method of claim 6, wherein a first portion of the distalportion of each of the plurality of wires is coupled to the outersurface of the first annular element, a second portion of the distalportion of each of the plurality or wires passes over the distal edge ofthe annular element, and a third portion of the distal portion of eachof the plurality of wires passes within the annular element proximatethe inner surface of the annular element.
 8. The method of claim 1,wherein the second annular element includes a proximal face and a distalface, the proximal face being configured to be releasably engageablewith a distal tip of a medical device.
 9. The method of claim 1, furthercomprising a control unit including a processor, the processor beingconfigured to receive signals from the at least one sensor element. 10.The method of claim 9, wherein the processor causes the control unit togenerate an alert based at least in part on signals received from the atleast one sensor element.
 11. A method of evaluating tissue, the methodcomprising: advancing a balloon catheter having an uninflated balloonthrough a lumen of a sheath, the sheath including a first annularelement coupled to a distal portion of the sheath, a plurality of wirescoupled to an outer surface of the first annular element, and a secondannular element coupled to an elongate wire conduit, at least a portionof each of the plurality of wires being disposed through the secondannular element and within the wire conduit, the wire conduit, secondannular element, and at least a portion of each of the plurality ofwires being disposed within the sheath lumen, at least one of theplurality of wires including at least one sensing element; releasablyengaging a distal tip of the balloon catheter with the second annularelement; advancing the balloon catheter through the sheath lumen untilthe uninflated balloon, the second annular element, and at least aportion of each of the plurality of wires are located distal to thedistal portion of the sheath; inflating the balloon, at least a portionof each of the plurality of wires being disposed over the inflatedballoon; and recording a physiological measurement with the at least onesensing element.
 12. The method of claim 11, wherein the at least onesensing element is at least one of a temperature sensor and a mappingelectrode.
 13. The method of claim 12, wherein each of the plurality ofwires includes a temperature sensor and a mapping electrode.
 14. Themethod of claim 13, wherein one of the plurality of wires furtherincludes a reference electrode.
 15. The method of claim 11, furthercomprising: retracting the balloon catheter, the second annular element,and at least a portion of each of the plurality of wires within thesheath lumen; and further retracting the balloon catheter within thesheath lumen until the distal tip of the balloon catheter disengagesfrom the second annular element.
 16. The method of claim 11, wherein thefirst annular element is coupled to an outer surface of the distalportion of the sheath.
 17. The method of claim 11, wherein releasablyengaging a distal tip of the balloon catheter with the second annularelement includes releasably engaging the distal tip of the ballooncatheter with a proximal face of the second annular element.